Apparatus for continuously carbonizing coal



April 13, 1965 E. s. BAILEY APPARATUS FOR CONTINUOUSLY CARBONIZING COAL Filed Dec. 15. 1960 United States Patent 3,178,361 APPARATUS FOR CONTINUOUSLY CARBONIZING. COAL Ervin G. Bailey, Easton, Pa., assignor to Bailey Inventions, Inc, Easton, Pa., a corporation of Pennsylvania Filed Dec. 15, 1960, Ser. No. 75,998 3 Claims. (Cl. 202-118) This invention relates to the carbonization of coal and more particularly to apparatus for carbonizing coal into char or coke in a continuous feed operation, as distin-- guished from the batch operations of gas retort, beehive and by-product coke ovens, while recovering volatiles and distillates;

Continuous motion of coal during its carbonization has great advantages since the motion permits constant agitation and some squeezing to produce a denser char, the mass is constantly being broken up so that the formation of salamanders is prevented and the char emerges from the retort as a free-flowing material which will not cake on chain or traveling grate stokers and will burn in vertical fired beds as a free-flowing material. Continuous motion also permits a stage distillation of volatiles for separate recovery. 7

Apparatus of this invention takes into account the tendency for bituminous, sub-bituminous and semi-bituminous coals to swell when they reach 600 to 700 F. temperature and makes provision for such swelling by a feedback arrangement which handlesthe excess volume resulting from the swelling action of the mass. For this purpose the apparatus utilizes as the continuous feed mechanism a pair of forwardly driving self-cleaning intermeshing screws plus a feedback screw operating in the reverse direction. Since feedback also aids in conditioning the raw material as it enters the intermeshing screws, the feedback arrangement can be constructed to handle not only the excess volume due to swelling but also any desired additional proportion of the material advancing through the retort.

Such an apparatus is shown in the accompanying drawings, wherein:

FIG. 1 is a diagrammatic vertical cross-sectional view of the retort broken away to indicate extent;

FIG. 2 is a plan view taken along the line 2-2 of FIG. 1; and

FIG. 3 is a side elevational view of the apparatus shown in FIGS. 1 and 2, along line 33 of FIG. 1.

The apparatus comprises a housing 3 having proper supporting bearings for its primary intermeshing screws ill and 2.0 driven at identical speeds through worm 22 and for an overlying feedback screw 24 driven in an opposite direction by a separate worm 26.

Intermeshing screws and 2% are hollow and communicate with a heating gas inlet header 3t) and a gas outlet header 32.

An overhead coal supply inlet is provided at 40 and a char outlet at the opposite end of the retort at 42.

Off-takes for the removal of tars and distillates and the recovery of hydrocarbons and gases are located at 44 and 46.

Beneath the housing 8 for the screw conveyors is a casing 47 providing a channel for circulation of heating gas from an inlet 48 near the char discharge end of the retort towards the coal supply end of the retort and through outlet 50.

With such retort, coal is fed in at supply 40 and as it is driven by intermeshing screws fill and towards the discharge end it encounters the increasing heat provided from heating gases circulating in a counter direction both within the casing 47 and within the hollow intermeshing screws to preliminarily raise its temperature to about r ce 2 500 to 600 F. thus partially melting the coal and driving off tar and hydrocarbon volatiles present in the coal.

Further advance of the hot material towards the discharge end of the retort subjectsit to continuing rising temperature which decomposes other less volatile materials and drives them oil? as gas distillates exhausting'through outlet 46 for recovery and use by well-known methods. The constant agitation of the mass aids in release of such materials and the swelling encountered by the treatment tends to lift a portion of the material up into the path of the counter-rotating screw 24 thus returning such material into the path of the incoming raw coal which aids in mixing and preventing agglomeration of the incoming material.

In the case of certain high volatile coals, it is desirable to feed back a greater proportion of the advancing material, e.g., even as much as 50 percent over and above the swelling factor. Accordingly the screws 10 and 20 are shown in the drawings as having a uniformly decreasing pitch from right to left, so that the pitch at the discharge end of the retort is about one half the pitch at the coal entering end. The pitch can however be otherwise varied either uniformly or non-uniformly to cause any desired proportion of the material to be lifted up into the path of feedback screw .24. Where the pitch is not varied along the length, it will be understood that the amount fed back very nearly corresponds to the excess volume due to swelling only.

The gases issuing from the retort are of similar composition and quality to that of the conventional tar, heavy hydrocarbons and illuminating gas produced by by-product coke ovens. However, in the present retort the tars and heavy hydrocarbons are taken ofr primarily at 44, separate from the lighter hydrocarbons including the illuminating gas which is released primarily at 46. All of these materials may be used as with coke oven byproducts for well-known chemical processes or for burn ing, as desired.

in order to drive off the lighter hydrocarbons, the heating gases are fed in through header 3% and through inlet 48 at temperatures of 1000 F. or more, which in heat exchange relation wtih the countercurrent flow of material being treated, provide a 500600 F. temperature near the gas outlet end. r

The char emerges from the retort nodulized into lumps free from fines and dust.

In some cases the coal charge may be intermixed with minerals or fluxes to lower or raise the fusing temperature of ash released from later burning of carbonized coal.

What is claimed is:

1. Apparatus for carbonizing coal comprising a stationary retort, means for feeding coal into a supply end of said retort, a pair of substantially horizontally extending intermeshing screws supported in said retort, means for continuously rotating said screws in the same direction to move coal supplied by said feeding means at said supply end of said retort toward the other discharge end of said retort, means for feeding hot gas through said retort in indirect heat exchange relation with said coal from the discharge end thereof towards the supply end thereof, separate outl ts spaced along said retort for removing volatiles and distillates released in the portion of the retort near the supply end of said screws separately from volatiles and distillates released in the portion of said retort near the discharge end of said screws, a feedback screw lying over and between said screws and means for operating said feedback screw to convey at least a part of the material passing through said retort lifted out of the paths of rotation of said intermeshing screws, back towards the supply end of said retort for mixing with incoming material and refeed through said retort.

Patented Apr; 13, 1965 i 2. Apparatus as claimed in claim 1, wherein said intermeshing screws are hollow, said apparatus having headers connected to opposite ends of said hollow intermeshing screws, and means for passing hot gases from the header which is connected to said screws at the discharge end of said retort through said hollow intermeshing screws towards and into the header which is connected to said screws at the supply end of said retort.

3. Apparatus for carbonizing coal as claimed in claim 1, wherein said intermeshing screws have decreasing pitch along their length from the supply end to the discharge end of said retort to aid in lifting material moved by said screws along said retort up into the path of said feedback screw.

References Cited in the file of this patent UNITED STATES PATENTS Smith et a1 May 9, 1922 Easton Sept. 18, 1923 Kinyon Sept. 15, 1925 Hertel Dec. 2, 1930 Jackson Apr. 5, 1938 Tuttle Sept. 5, 1944 Danulat et a1 May 9, 1961 Siebring Apr. 24, 1962 FOREIGN PATENTS Great Britain Feb. 15, 1873 Great Britain Feb. 28, 1924 

1. APPARATUS FOR CARBONIZING COAL COMPRISING A STAIONARY RETORT, MEANS FOR FEEDING COAL INTO A SUPPLY END OF SAID RETORT, A PAIR OF SUBSTANTIALLY HORIZONTALLY EXTENDING INTERMESHING SCREWS SUPPORTED IN SAID RETORT, MEANS FOR CONTINOUSLY ROTATING SAID SCREW IN THE SAME DIRECTION TO MOVE COAL SUPPLIED BY SAID FEEDING MEANS AT SAID SUPPLY END OF SAID RETORT TOWARD THE OTHER DISCHARGE END OF SAID RETORT, MEANS FOR FEEDING HOT GAS THROUGH SAID RETORT IN INDIRECT HEAT EXCHANGE RELATION WITH SAID COAL FROM THE DISCHARGE END THEREOF TOWARDS THE SUPPLY END THEREOF, SEPARATE OUTLETS SPACED ALONG SAID RETORT FOR REMOVING VOLATILES AND DISTILLATES RELEASED IN THE PORTION OF THE RETORT NEAR THE SUPPLY END OF SAID SCREWS SEPARATELY FROM VOLATILES AND DISTILLATES RELEASED IN THE PORTION OF SAID RETORT NEAR THE DISCHARGE END OF SAID SCREWS, A FEEDBACK SCREW LYING OVER AND BETWEEN SAID SCREW AND MEANS FOR OPERATING SAID FEEDBACK SCREW TO CONVEY AT LEAST A PART OF THE MATERIAL PASSING THROUGH SAID RETORT LIFTED OUT OF THE PATTHS OF ROTATION OF SAID INTERMESHING SCREWS, BACK TOWARDS THE SUPPLY END OF SAID RETORT FOR MIXING WITH INCOMING MATERIAL AND REFEED THROUGH SAID RETORT. 